Abstract: The regularity of sea-level changes is one of the most important aspects of sequence stratigraphy.Usually,only the relative changes in water depth can be assessed;the sea-lev-el changes are difficult to be understood directly from the study of outcrop sequences.So how to extract the information of sea-level changes from the outcrop sequences becomes a very difficult problem confronting us.The methods of mathematics and developed Fischer Plots have been introduced in this paper to reconstruct the sea-level changes based on the stratigraphic sequences deposited in the shallow peritidal environments.The sea-level changes in the Cambrian strata in the Xiao'erbulake region of northern Tarim Basin have been reconstructed with the aid of these methods,and the results are satisfactory.